1. Technical Field
The present invention relates to a method of manufacturing a member with concave portions, a member with concave portions, a lens substrate, a transmission type screen and a rear projection, and more specifically to a method of manufacturing a member with concave portions, a member with concave portions which is manufactured using the manufacturing method, a lens substrate manufactured using the member with concave portions, a transmission screen provided with the microlens substrate, and a rear projection provided with the transmission screen.
2. Related Art
In recent years, there is an increasing demand for rear projections that serve as displays suitable for use in home theater monitors, large-screen televisions and the like. A transmission type screen having a lens substrate (lenticular lens substrate) with lenticular lenses is generally employed in the rear projections.
From a stand point of viewing angle characteristics and so forth, attention is recently being paid to a lens substrate (microlens substrate) that employs microlenses in place of the conventionally used lenticular lenses (see, e.g., JP-A-2004-286906)
In general, the lens substrate as noted above is manufactured using a mold that has a shape corresponding to lens portions (lenticular lenses, microlenses or the like) of a lens substrate targeted for manufacture. Such a mold is produced by, e.g., etching through the use of a mask having openings at its locations corresponding to lens portions (concave portions) which are to be formed on the lens substrate.
In the case where the concave portions are formed on the mold by etching, however, a severe change appears in an etching amount depending on the temperature of an etching solution, the composition thereof or the like. This makes it difficult to reliably manufacture a mold having concave portions of a desired size and shape (e.g., a desired radius of curvature).
Further, the composition of an etching solution varies over time by reiterative etching treatments or other causes. This poses an even severe difficulty in controlling the etching amount.
Such an inability to reliably control the etching amount makes it impossible for the resultant lens substrate to have required optical characteristics, thereby reducing the reliability of the lens substrate and a rear projection provided with the lens substrate.